They say that a picture is worth a thousand words. While this may be true if picture is a schematic of a complicated gizmo you're trying to put together, it is hardly case when it comes to your ads.
An image should be used to get attention, and it should draw people in to read words used in ad. Words sell - not pictures. Each word used in ad should lead person to desired outcome. In case of a classified ad, desired outcome should be to have them request more information. Sales are seldom made from first ad someone sees describing your product, service or opportunity. If you can get someone to ask for more information, your ad has done first part of job.
Anyone involved in Internet Sales without a web page is simply spinning their wheels. Many of web pages however are disaster areas. People get so creative in their design, they forget their primary purpose. Once you have gotten someone to this point, it is now time to close sale, and this is where many people "miss boat".
Think about it - your ad had to have been effective as it got them to your web site. They are looking for additional information. Some people want presentation in quickest possible fashion, while others are willing to spend time researching your offer. To be effective you should try to accommodate both groups.
An effective presentation will provide a synopsis of what you want to cover. It should also have a "link" where a person can be sent for in depth information. This is definitely a case where more is better. But you should not use words simply to fill space - they should all be carefully crafted to bring person to your order page.
Studies have shown that one large web page with internal links to additional information will rank better with search engines. Think of these internal links as bookmarks within your page, which will quickly advance someone to desired spot.